sanitation technology options in informal settlement: a...
TRANSCRIPT
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Sanitation technology options in informal settlement: a system dynamics
approach
Paul Currie1, Jack Radmore
1, Josephine K Musango
*2 & Alan C Brent
3
* Correspondence Author, [email protected] 1Student, Master in Sustainable Development, School of Public Leadership, Stellenbosch; Email: [email protected];
[email protected] 2TSAMA Hub, School of Public Leadership, Stellenbosch University, Private Bag X1 Matieland, 7602; South Africa
3Department of Industrial Engineering and the Centre for Renewable and Sustainable Energy Studies (CRSES)
Private Bag X1, Matieland, 7602, South Africa; Tel: +27 21 808 4069; Email: [email protected]
Abstract
Provision of sanitation services to urban informal settlement is one of the challenges that the
urban planners and decision makers are face with in the current era. High population growth and
lack of legal status in informal settlements makes it challenging to improve the level of
sanitation. The question then is whether there are possible technology options that can be utilized
to achieve sanitation crisis in informal settlements. This paper thus delves into the dark and
complex world of the sanitation crisis in informal settlements. Using system dynamics approach,
it describes the key elements in the sanitation provision in informal settlements, and specifically,
in the context of Enkanini, an illegal informal settlement in Stellenbosch. The system dynamics
model demonstrates differences between four sanitation technologies, namely: pour flush;
ventilated improved pit latrine; compost toilet; and regular toilet. The results show that there is a
long-term benefit from waterborne sanitation, as well as rapid improvement in sanitation from
cheaper options of a compost toilet and ventilated improved pit latrine. The pour flush toilet and
ventilated improved pit latrine occupied the beneficial middle ground of minimal investment for
decent output in sanitation improvement as well as improvement of the sanitation experience.
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1 Introduction
“Dignity is at the core of all human rights, and lack of sanitation, more than many other
issues, threatens that concept. Ensuring that all have access to sanitation is a step
towards ensuring a more dignified life for all.”
(Catarina de Albuquerque, Independent Expert, Office of the United Nations High Commissioner for
Human Rights)
Provision of sanitation technology solutions in urban informal settlements is extremely
challenging due to: (i) lack of legal status of the settlement area; (ii) poor accessibility; and (iii)
lack of interest by inhabitants to invest in sanitation (Paterson et al., 2007, Katukiza et al., 2010,
Katukiza et al., 2012). Sanitation can be regarded as the management of human excreta, solid
waste, and grey and storm water (Katukiza et al., 2010).
It is estimated that about two billion people live with inadequate sanitation (Paterson et al.,
2007). More than two million people (mostly children) die each year from diseases associated
with inadequate sanitation and lack of safe drinking water (Paterson et al., 2007). The battle
against inadequate sanitation is not merely about containing the spread of fatal diseases; access
to adequate sanitation is vital to human dignity, safety, environmental sustainability, poverty
reduction and general psychological well-being (Socio-Economic Rights Institute of South
Africa (SERI). 2011). The reality of the daily sanitation struggle for millions of peri-urban
residents is a stark reality indeed; it represents one of the major challenges of the 21st Century,
one which humanity is still far from overcoming (Paterson et al., 2007). This challenge cannot be
seen as being simply a technical foe; instead it must be understood as a socio-technical problem,
deeply rooted within multiple complex and intertwined systems, compounded by the complexity
of second wave of urbanisation (Tavener-Smith, 2013). In the second wave of urbanisation, the
period between 2005 and 2050, global population is expected to reach 9 billion, and out of this,
6 billion people will live in the cities (United Nations Department of Economic and Social
Affairs., 2010, UNEP., 2012). For Sub-Saharan Africa, already 62% of urbanites live in slums,
and 800,000 new urban dwellers are expected by 2050, which will most likely increase this
percentage (Robinson et al., 2013).
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In the case of South Africa, vast population growth is being experienced in peri-urban informal
settlements (Mels et al., 2009). This implies that providing adequate water and sanitation for the
growing population is becoming increasingly difficult, bearing in mind of already existing
service delivery woes and the complex environmental, socio-economic and cultural limitations
plaguing informal settlements (Mels et al., 2009).
The right to access adequate (standard) sanitation is not specifically catered for in the
Constitution of South Africa; however, there are a number of different instances within the
constitution which directly or indirectly imply the right (Socio-Economic Rights Institute of
South Africa (SERI). 2011). According to World Health Organization (2012), adequate
sanitation includes sanitation facilities that hygienically separate human excreta from human
contact. Since 2007, the South Africa Department of Water Affairs has made efforts to eradicate
the use of the inadequate sanitation systems – commonly known as bucket system. Despite these
efforts, there are still millions of people who are forced to use the bucket and other unacceptable
systems (Socio-Economic Rights Institute of South Africa (SERI). 2011). The majority of the
people existing without adequate sanitation live in already bulging yet continually sprawling,
informal settlements. Service infrastructures are strained, without the prospect of more people to
support.
This paper delves into the dark and complex world of the sanitation crisis in informal
settlements. It describes the key elements in the sanitation provision in informal settlements, and
specifically, in the context of Enkanini, an illegal informal settlement in Stellenbosch. The
settlement is 40 km west of City of Cape Town and consists of about 8000 people serviced by
only 72 toilets (Tavener-Smith, 2013). In light of this predicted predicament, addressing the
sanitation issue provides an opportunity to explore the implementation of appropriate technology
options which more aptly suit the needs of the residents.
2 Sanitation situation in the City of Cape Town and Enkanini informal settlement
The City of Cape Town is home to more than 220 informal settlements, made up of a population
of approximately 900 000 people (Mels et al., 2009). Despite the City of Cape Town
Municipality’s goal to provide 100% access to basic water supply and at least 70% access to
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sanitation services to all informal settlements, sanitation coverage is still lagging behind (Mels et
al., 2009). Poorly maintained toilets are also evident in the informal settlements (Figure 1)
Figure 1: Poorly maintained toilets in informal settlements in Cape Town
According to official statistics, around 36.5% of the population of informal settlements in Cape
Town are serviced with basic sanitation; in reality, this number is considerably lower (Mels et
al., 2009). In this case the disparity has two main causes; firstly, the officially accepted number
of people living in informal settlements is dramatically lower than the actual number (Mels et al.,
2009). Secondly, these statistics also include bucket toilets and eradicate containers as basic
sanitation, which the majority of experts agree are not sanitation options at all; taking these
details into consideration, the percentage of people in informal settlements provided with basic
sanitation is estimated to be around 15% (Mels et al., 2009).
One of the informal settlement struggling from a lack of basic sanitation services is Enkanini,
which is an illegal, informal settlement consisting of around 8000 people, which also translates
to approximately 2500 households (Tavener-Smith, 2013). According to Shark Dwellers
International (2012), the ratio of people to toilets is approximately 72:1 and, of the 80 existing
toilet blocks, 9 were in desperate need of maintenance while 9 were vandalised (see Table 1) . It
should be noted that the aspiring South African standard ratio for people to toilets is 5
households per toilet (City of Cape Town., 2008). The distribution of these toilets paired with
recent violent acts has led to an increase in unequal access, with some 90% of residents
expressing fears of using unlit toilets at night (Shack Dwellers International., 2012).
Table 1: Summary of key findings of enumeration in Enkanini
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Name of settlement Enkanini
Age of settlement 7 years (2006)
Type of structures All shacks
No. of shacks 2494
Land ownership Municipality
No. of community toilet blocks 80, 9 need maintenance and 9 vandalised
Ratio of toilets/population 1:72
Water taps 32, all functional and well maintained
Ratio of water taps/population 1:139
Disaster experience Mainly fire (111) and flooding (840)
Source: Adapted from Shack Dwellers International (2012)
The pressures of insufficient sanitation in Enkanini informal settlement are expressed differently
depending on whom you ask; but seeing that conventional water supplied sanitation has proved
immensely inadequate in a resource and topography constrained Enkanini (see Figure 1), a
group of students from the University of Stellenbosch have begun to look at possible alternatives
(iShackliving, 2012). This is where the inspiration came from to analyse the effect that different
sanitation technologies have on the standard of sanitation.
Figure 1: Photos from the Informal Settlement of Enkanini (taken by J Radmore)
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Working side by side with Enkanini residents and the Stellenbosch Municipality in a
transdisciplinary co-production process, the group is seeking to conceptualise alternative
sanitation solutions (iShackliving, 2012). Many different solutions have been explored, ranging
from compost toilets to the use of ventilated improved pit latrines (VIP). The focus has now been
placed on the use of pour flush toilets connected to a bio-gas digester, at a ratio of five
households per toilet (iShackliving, 2012).
The fact that this is not merely a technical problem has not been forgotten (iShackliving, 2012).
Along with the analysis of alternative technologies, the Enkanini Sanitation Cooperative (using
the co-production, transdisciplinary process) has begun to explore alternative techniques for
governing and maintaining this complex system (iShackliving, 2012). Tracking and developing
residents’ demand for improved sanitation and building local supply and maintenance capacity
are two keystone interventions that the Cooperative are seeking to implement in Enkanini
(iShackliving, 2012).
The group has yet to find a ‘perfect’ solution and is very interested in being able to track the
viability of different sanitation technologies as well as the effect it could have on the standard of
sanitation, taking into account community demand, community temperament and actions,
functionality, dignity, and attached value to name but a few (Tavener-Smith, 2013).
The definition of basic sanitation as described in the City of Cape Town’s Water and Sanitation
Service Standard is as follows; “The provision of a shared toilet (at a ratio of not more than 5
families per toilet) which is safe, reliable, environmentally sound, easy to keep clean, provides
privacy and protection against the weather, well ventilated, keeps smells to a minimum and
prevents the entry and exit of flies and other disease-carrying pests; and the provision of
appropriate health and hygiene education.” (City of Cape Town., 2008).
The standard of sanitation in Enkanini is well below the national average, it is therefore obvious
that there is an inadequacy of sewage management and disposal. This inadequacy is made
obvious by the gap existent between actual or existing standard of sanitation in informal
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settlements and the expected standard of sanitation. This gap represents the specific problem
being model, using systems dynamics.
3 Model description
System dynamics represents complex systems and analyses their dynamic behaviour over time
(Forrester, 1961). According to Coyle (1996): “system dynamics deals with the time dependent
behaviour of managed systems with the aim of describing the system, and understanding,
through qualitative and quantitative models, how information feedback governs its behaviour,
and designing robust information feedback structures and control policy through simulation and
optimization”. Thus, the main objectives of system dynamics approach are (Sterman, 2000,
Maani and Cavana, 2007, Ford, 2010): (i) to clarify the endogenous structure of a particular
system of interest under study; (ii) to identify the interrelationships of different elements of the
system under study; and (iii) to account for different alternatives for simulation and explore the
changes in the system under consideration.
Different scholars have organised system dynamic modelling process as following a number of
steps, varying from three to seven different stages (Randers, 1980, Richardson and Pugh, 1981,
Roberts et al., 1983, Wolstenholme, 1990, Sterman, 2000). Following Sterman (2000), the
process of system dynamics modelling begins with problem identification and definition, where
the problem and the objective of the analysis are clearly described. This is followed by
conceptualisation where the boundaries and identification of causal relations are described. This
stage forms the qualitative analysis. The next step is to develop a formal and simulation model
utilising system dynamics software packages. Once the model is developed, the modeler is
required to test the model reliability and validity before undertaking policy analysis.
For the case of this paper, it was identified that a gap exists between the expected standard of
sanitation and the actual standard of sanitation in informal settlements. As the standard of
sanitation improves the gap will decrease, this increase in the standard of sanitation will also,
with a delay, result in an increase in the sanitation expectation; this follows a simple assumption
(mental model) that the more someone has, the more they want. As sanitation expectation grows,
the gap between actual and current sanitation also grows (Figure 2).
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Current Standard
of Sanitation
Expectation for
Sanitation
Gap
+
+ -
Figure 2: Sanitation problem identification
3.1 Qualitative analysis – causal loop diagram
The first stage of making a causal loop diagram requires identifying the key variables.
Table 2 shows these identified variables and how they were defined for the purpose of the
sanitation problem in informal settlement. The sub-sections that follow describe the dynamic
hypothesis of the problem.
Table 2: Variables considered in the CLD
Causal Loop Variables
Current standard of
sanitation
The current standard of sanitation within the settlement taking into
account the “percentage of the population using improved sanitation
facilities (World Health Organisation., 2012)
Expectation for
sanitation
The standard of sanitation the individuals within the settlement
expect. Using a simple assumption that the more someone has the
more they will want
Gap The difference that exists between the current standard of sanitation
and the expected standard of sanitation.
User temperament The general disposition of the individual user of the sanitation
services. How the people within the settlement feel about the
sanitation situation. Can be either positive or negative.
User conduct The actions of residents that result from their temperament, they can
care for the existing facilities (or not), engage positively with the
service provider, protest or vandalise toilets depending on their
current disposition.
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Serviced population The amount of people that have adequate access to the sanitation
facilities taking into account the population, the serviceable
population and the sanitation experience.
Sanitation experience The individual’s experience when making use of the sanitation
facilities taking into account the user’s dignity, safety, aesthetics of
living space, privacy, and attached value.
Cleanliness of facilities The general cleanliness of the facilities. The containing unit as well
as the toilet itself.
Service provider
accountability
The accountability of the service provider, this determines whether
or not the facilities are maintained, cleaned and serviced. This
declines naturally at a constant rate and is can also be influenced
through public action (protest).
Need for additional
intervention
If the sanitation problems, vandalism and protest, within the
settlement, become too large additional intervention will be needed
by either government or private institution.
Emergency budget The amount of money provided by the intervention team to solve the
growing problem
Serviceable population The number of people, taking into account policy required number
of people per toilet and the number of existing number of toilets, that
that can be adequately serviced.
Number of functioning
facilities
The number of working and clean toilets facilities within the
settlement.
Prevalence for disease The probability or frequency of disease spreading through the
settlement
Health The general health of individuals living in the settlement
Population The mount of people living in the settlement, taking into account the
rate of birth and death.
External defecation The practice of relieving oneself in open areas, this also takes into
account the use of bucket toilets.
Toilet decommissioning
rate
The rate at which toilets degrade, to a point where they are no longer
usable
Enviro impact The impact that the external defecation has on the environment.
3.1.1 Main sanitation loop
The dynamics within the informal settlement sanitation problem is mainly dependent on the
sanitation gap (Figure 3). As the gap increases, it in-turn decreases user temperament. As user
temperament develops a negative trend, user conduct (actions) begins to deteriorate, resulting in
protests, decreased care of the toilets and vandalism. As this worsens, conduct begins to
influence the functionality of the facilities negatively (reduced care, vandalism), thus the number
of people who have access to functioning facilities decreases. As the serviced population
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decreases, the sanitation experience (users’ dignity, safety, aesthetics and privacy etc.) decreases,
further decreasing the standard of sanitation, creating a reinforcing causal loop as seen in Figure
3
Current Standard
of Sanitation
Expectation for
Sanitation
Gap
+-
User Temperament
(Satisfaction)
User Conduct
(Protest, care etc.)
Serviced population
(Access)
Sanitation
Experience (Senses)
-
+
+
+
+
R
Main sanitation
Loop
Figure 3: Main causal loop for sanitation
3.1.2 Health, the environment and toilet decommissioning loop
As more people begin to practice bucket or external defecation there is an increase in
environmental impact, decreasing the sanitation experience. The better the experiences, the better
the current standard of sanitation. This increases the gap, which in-turn decreases user
temperament. As user temperament develops a negative trend, user conduct (actions) begins to
deteriorate, resulting in protests, decreased care of the toilets and vandalism. This is shown in
environment loop in Figure 4.
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Current Standard
of Sanitation
Gap
-
User Temperament
(Satisfaction)
User Conduct
(Protest, care etc.)
Enviro
Impact
Serviced population
(Access)
external
defecation
Sanitation
Experience (Senses)
-
+
+
+
-
+
-
Environment
loop
B
Serviceable
population
Prevalence for
disease
Serviced population
(Access)
external
defecation
Population
+
-
-
+
+
+Health
+
Health loop
B
Figure 4: Health loop and environment loop
As fewer people have access to adequate facilities (serviced population) more people begin to
practice bucket or external defecation, resulting in an increase in the prevalence of disease,
decreasing the general health of the settlement and ultimately the population. As the population
decreases the serviceable population (number of people that can be furnished with an adequate
facility given the number of toilets) increases, as shown in health loop, which is a balancing one.
3.2 The model
Developing stock-and-flow model required classifying and identifying which are the endogenous
variables, exogenous and excluded one. Table 3 presents the boundary map for the sanitation
model. Vensim DSS was utilized to develop the model. The time-step for the model was in
months and was simulated for 240 months. The model sub-models are discussed in the
subsequent section.
Table 3: Variables considered in the formal model; key variables are in bold.
Endogenous Exogenous Excluded
Stocks Flows Auxiliaries Parameters Excluded
Population Births
Deaths
Death-rate Initial Population
Birthrate
Base Death-rate
Migration
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Endogenous Exogenous Excluded
# of Toilets New Toilets
Decommissioned
Toilets
Destroyed Toilets
New toilets needed
Potential toilets to install
Monthly Budget
Emergency Budget
Cost of Toilets
Building Delay
Vandalism Rate
Decommissioning Rate
Initial # of Toilets
Initial service provider
budget
Who service provider is
Accountability More / Less Loss of motivation Profit
Governmental attention
External Waste External defecation
Biodegradation
Total human waste per month
Likelihood of external defecation
Average waste per person
per month
Half-life of Human Waste
Area Impacted per
Kilogram
Initial prevalence for
disease
Size of Settlement
Effect of Runoff Water
Standard of Sanitation
Serviced Population
Serviceable Population
Choice of Technology
Policy-Req people per toilet
Importance of senses to
sanitation
Effect of external
defecation on senses
(their dignity etc)
Senses Fulfilled
Safety
Dignity
Privacy
Attached value
Aesthetic value
Current privacy level
Current Toilet Distribution
Hygiene education
Optimum privacy level
Optimum toilet distribution
Rate of learning
Initial hygiene education
level
Cleanliness of Facilities
Needed servicing
Actual servicing
Proportion of serviced facilities
Expectation of Sanitation
Gap Between Expected and
Actual Sanitation
User Temperament
Care
Positive Engagement
Protest
Violence & Vandalism
Emotional Volatility
Expectation Creation date
Minimum Expectation
Effect of senses on
expectation
Prevalence for Disease
Initial prevalence for
disease
3.2.1 Sub-Models
(i) Population sub-model
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The population was determined using one stock, demonstrating growth through births and
reduction with deaths (Appendix 1). The prevalence for disease, an auxiliary determined by
sanitation’s impact on health, is a factor multiplied to the death-rate as it has influence on the
death rate.
(ii) Sanitation Experience (Senses Fulfilled) sub-model
The senses of dignity, privacy, aesthetic value and attached value are each given an intrinsic
value by the choice of technology, following the notion that each technology will affect these
senses differently (Appendix 2). Dignity is further affected by the users’ engagement with the
service provider; positive engagement shows more dignity and protest shows decreased dignity.
This can be interpreted as the engagements directly changing a person’s dignity or as a reflection
of the dignity required to take these actions.
Privacy is further affected by the number of people having to use each toilet. This is
demonstrated using an optimum privacy level (set at 5 people per toilet - one household). The
current privacy level uses the current number of toilets to show how many people are receiving
optimum privacy out of our total population. Aesthetic value is further affected by the
environmental impact. As the impact increases, aesthetic appreciation for the living area will
decrease to a point at which it becomes an accepted norm (stable).
Attached Value of the Technology is further affected by hygiene education, particularly relating
to how people value their toilets. This is presented as a potential policy intervention which can
be switched on or off, and is determined by an initial education level of the settlement and a rate
of learning. Improvements to this could involve a way to change the rate of learning over time, to
change hygiene education into a stock, and include a trigger mechanism (if for example the
sanitation level drops below a certain point). The baseline sets the initial level at 0.3 and the rate
of learning at a static 0.005/month.
Finally, safety is determined by proximity of the user’s home to a toilet. In an unstable
settlement, the farther the toilet is from the home, the less safe it is to go and use it, particularly
after dark. The model assumes an even distribution of toilets, which is not necessarily realistic. It
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compares the optimum distribution of toilets to the current distribution; current distribution is the
current number of toilets divided by the area of the settlement. This sense could be improved
with development of a base danger level inherent in the settlement and a more realistic way to
show toilet distribution, perhaps with an average distance to household. The baseline has the
optimum distribution at 1 toilet per 20 square meters (a maximum 10 meters from the
household), and the size of the settlement is 50,000 square meters. Safety is also diminished by
the occurrence of protest and violence in the area.
It should be noted that senses can be influenced by a number of external factors, but for the sake
of the model, they express only how sanitation influences them. The senses are informed by the
technology type, but much isn’t shown about the sanitation experience for those who aren’t using
a toilet. Privacy somewhat includes this by making a ratio of those ‘with privacy’ and those
without.
(iii) Health and Environmental Impact
If a person does not have access to a toilet, then they will find somewhere to do their business;
this is called external defecation and has huge impacts on the environmental and human health of
the area (Appendix 3). The likelihood of external defecation is the proportion of unserviced
people out of the total population.
Health impact is expressed as the prevalence for disease, which may have an initial rating for the
area and increases: to a maximum of 60% as external defecation increases (this is based on the
likelihood of getting cholera from contaminated water); to a maximum of 30% as the cleanliness
of the facilities decrease.
For the model, environmental impact is simplified to the area affected by improper feces disposal
out of the total area of the settlement. The waste is presented as a stock which is increased over
time by external defecation (percentage of people doing so multiplied by the total waste
generated in the settlement), and decreased as the waste biodegrades. These both are served by
two parameters, the average amount of waste generated per person (~300g per day or 10kg a
month for the baseline) and the half-life of human waste (1kg per year or 1/12kg per month for
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baseline). This remains logical; however the model then determines the area impacted by this
waste in a way that assumes waste can only be deposited on fresh ground (land affected per kg of
waste - .25m2 per kg for baseline), therefore assuming an even distribution of impact throughout
the settlement.
(iv) Number of Toilets
Number of toilets is represented by one stock, which is increased by a flow of new toilets and
decreased by flows of decommissioned toilets and toilets destroyed through vandalism
(Appendix 4). The model assumes that toilets will only be built if they are needed, needed toilets
being determined by the national policy-required number of people per toilet. They can only be
built if there are funds available to do so; such funding can come from a monthly service
provider budget, or from emergency funding (perhaps from the government or private
institution) when the sanitation level is observed to go below 0.2; the emergency funding is
enough money to pay for all the needed toilets. The number of toilets which can be built from
this budget is determined by the cost of the toilets (dependent on the choice of technology). The
length of time it takes to build the toilets is dependent on how accountable the service provider
is, taking anywhere from a month to six.
Toilets are destroyed if instances of vandalism and violence occur; the vandalism rate rises
slowly to 3% from no vandalism before rising rapidly to a maximum of 30% as people get much
angrier. Toilets are decommissioned according to the life expectancy of the technology (choice
of technology) and how well maintained they are (cleanliness of facility). If maintenance is high,
the decommissioning rate can be reduced by up to 20%, and alternately, if maintenance is low,
the decommissioning rate can increase by up to 20%.
The only two parameters for toilets are the initial quantity, set at 66 toilets (the population
divided by the policy-required 15 toilets) for the baseline, and the initial budget, set at 0 to show
an expected decline in sanitation.
(v) Cleanliness of the Facility
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The cleanliness of the facility is determined by the proportion of facilities which are serviced,
which is in-turn determined by how often it needs to be serviced and how often it is actually
being serviced (Appendix 5). The choice of technology informs how often it must be serviced,
and the accountability of the service provider determines how often this is actually being done.
Whether or not users care for the facilities also affects the level of cleanliness; as care increases,
cleanliness can maximally double, and if it decreases, cleanliness can maximally halve. Should
one wish to remove functionality or cleanliness from their definition of sanitation, the switch
would allow this.
(vi) Accountability of the Service Provider
Accountability is represented as a stock for this model for simplicity of use (see Appendix 6).
The assumption is that without positive engagement, protest or profit, service provider
accountability will naturally decline (numerically shown in the loss of motivation variable). As
profit has been excluded, positive engagement and protest are the variables which increase
accountability (to larger degrees as they increase). It is further assumed that protest increases
accountability much faster than positive engagement. As an index, accountability ranges from 1
to 0.2 (assuming, optimistically, that accountability cannot drop below this), so the initial
accountability must be between this; baseline starts at 1. For the baseline, our accountability loss
is 0.01 per month. Should one wish to see the model without the effects of diminished
accountability, it can be turned off with the switch.
(vii) User Temperament and User Expectations
User temperament is what determines the user behaviors of care, positive engagement, protest,
and vandalism and violence (Appendix 7). With 0.6 as the neutral point, care is at 1 (neutral),
positive engagement, protest and violence are at 0 (not occurring). As user temperament gets
higher, care gets better and positive engagement begins and increases. As user temperament
decreases, care gets worse, and both protest and violence begin and increase. Care is further
influenced by hygiene education; as education increases, so does care (ranging from 80% when
education is below 1, to 120% when it’s above).
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To represent a feeling of humanity (and demonstrate the fluctuations feelings), a variable called
emotional volatility, which randomly increases or decreases user temperament by 1% each
month, is included.
The gap between expected and actual sanitation determines the user temperament. This was
difficult aspect to explore, simply because expectations are built from so many things which are
not easily explainable, let alone capable of being quantified. Expectations are based on past
experiences, what others have (the green-grass syndrome), altered by changes in other aspects of
one’s life, and e influenced by the hypothetical (dreams). This brings to questions such as:
Should expectations continue to grow? Should they be static? Are they always higher than what
one actually has? Can one remain happy with what one is receiving?
This warrants a model all on its own. Wishing to keep the influences endogenous, and retain our
feedback loops, we simplified expectations into what one had experienced before. The earlier
standard of sanitation is determined by the expectation creation date (how long ago one looks
back); for the baseline we used 12 months.
A difficulty with only using this is that if the gap between actual and expected is too small, no
action will be taken by the users; this is the case regardless of what their standard of sanitation is.
While one can logically understand that users will get comfortable receiving what they expect, it
doesn’t allow any endogenous improvement of sanitation. For this reason, a minimum
expectation was added to account for seeing the green grass over the fence. For the baseline, it’s
at 0.4, meaning that if sanitation dips far below that, users will do something about it. A better
improvement to this could be an outsider intervention, similar to the emergency funding for
toilets. Connecting the senses of sanitation (or perhaps the expectation inherent to each sense)
directly to the expectation of sanitation may also be a way to add dynamic to the expectations
(viii) Choice of Technology
The Choice of Technology has implications for each of our key variables, setting initial or
constant values for many parameters in the model using the function of a lookup table. The
variables it directly affects are the cost of, and decommissioning rate of toilets, base value for
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some of the senses, and the need for servicing the toilets. The technologies are each designated a
number, with Pour Flush Toilet at 0, Vent Pit Toilet at 1, Compost Toilet at 2, Traditional Flush
at 3, and a ‘neutral toilet’ at 4. The neutral toilet serves as the baseline, having no positive or
negative effects on the senses and taking the average of the selected technologies for the other
parameters. An example of how a lookup table is used to determine the users’ attached value of
the toilet is shown in Figure 5.
Figure 5: Users attached values to different technologies
Values assigned to each technology are demonstrated in Table 4 and Figure 6. Included in this is
the bucket technology, which was originally considered. This is essentially external defecation,
as the contents of the bucket are typically deposited in the same area. The model was altered to
include the effect of external defecation on environmental impact, and so we no longer include
bucket technology in the lookup tables. Environmental impact of technology is excluded from
the model, but this refers to any leakage of waste into the environment.
Table 4: Characteristics of different sanitation technologies
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Choice of
technology /
Parameters
Base (4) Pour Flush (0)
Ventilated
Improved Pit
(VIP) (1)
Compost toilet
(2)
Regular
toilet (3) Bucket
Life span (years) 32 35 35 10 50 5
Decommissioning
Rate (1/month) 0.0026 0.00238 0.00238 0.00833 0.0017 0.00017
Cost per unit (R) 5800 7000 4500 1700 10000 100
Frequency of
cleaning/servicing
Daily
/4years Daily/month Daily/2years Daily /8years
Daily/mon
th Never
Needs Servicing
(1/month) 0.625 15 1.25 0.313 15 0.001
Aesthetic value 1 1.2 1 0.8 1.5 0
Privacy 1 1.6 1.6 1.2 1.6 0.5
Dignity 1 1.2 0.9 1 1.5 0.2
Attached value 1 1.4 1.2 0.7 1.8 0
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Figure 6: Attributes attached to different sanitation technologies.
3.2.2 Baseline parameters
The baseline parameters and assumptions selected as inputs for Enkanini informal settlement was
established through an interview with Tavener-Smith (2013), who is a PhD student working in
Enkanini focusing on the sanitation problem, as well as the first two authors personal experience
as they are part of the Enkanini research team. The baseline parameters are presented in Table 5.
Table 5: Baseline parameters for Enkanini informal settlement
Name of settlement Enkanini
Age of settlement 7 years
Choice of Technology 4 (neutral tech for baseline) 0, 1, 2, 3, 4 (Technologies)
Policy-Required people per toilet 15 people/toilet
Population 8000
Birth Rate (SA average) 19.32 births/1,000 population – 0.01932
Death Rate (SA average) 17.23 deaths/1,000 population – 0.01723
No. of community toilet blocks 80, 9 need maintenance and 9 vandalised
Optimum privacy level 5 people/toilet
Initial Service Provider
Accountability
Loss of motivation
1
0.01
Initial Budget R230000 per year; R19166 per month
Acceptable number of people/ toilet 5 households per toilet (City of Cape Town, 2008: 11-
12)
Optimum toilet distribution 1/20m2
Emergency funding Twice the initial budget
Importance of sense to sanitation 40%
Emotional volatility 0.99-1.01
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Expectation Creation time 12 months
Minimum Expectation 0.4
Average waste per person/month 10kg
Half-life of Human Waste 1/12 kg / month
Area Impacted/Kilogram of waste 0.25m2 / kg
Size of Settlement 254000m2
Initial prevalence for disease 1
Rate of learning 0.005
Initial hygiene education level 0.03
Scenarios for different sanitation technology options were simulated in order to assess their
influence on the following variables; the (i) standard of sanitation, (ii) population, (iii) user
temperament (related to sanitation), (iv) number of toilets, (v) the sanitation experience (dignity,
safety, privacy etc.), (vi) the cleanliness and functionality of the facilities, (vii) service provider
accountability and (viii) the health and environmental impact related to sanitation.
4 Model testing and validation
Validation is an important step for creating a model. Barlas (1996) explains that for a causal-
descriptive model (any systems dynamics model), validation must not only look for an accurate
output, but at all the relationships which determine this behavior. Because such models are used
to test the effectiveness of policy changes or adaptations to the behavior, these relationships must
be explicit and simply influenced. Barlas (1996) offers two sequential validation procedures to
check the structure-oriented behavior and the behavior patterns, which include theoretical and
empirical structure tests, before moving onto structural behavior tests and then behavior pattern
tests. At each point, should a test fail, the model must be revised and re-tested. Finally the model
must be submitted for expert analysis to confirm the validity of the model (Barlas, 1996).
The model presented in this paper was subjected to structural and behavioral tests, following
each of the causal links and looking at overall patterns. The difficulty in engaging with a
complex problem is identifying a single behavioral effect from the system’s output. This is
addressed through the addition of parameter sensitivity analysis.
Within the bounds of our limitations, the model awaits a final step of expert consultation, which
will enable a thorough reworking of any magnitude issues.
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5 Results – Enkanini case study
The results for this case study are presented as follows:
• Comparative results for the four technologies
- Standard of sanitation
- Sanitation experience
- Number of toilets
- User temperament
• Scenario 1 – Causal interactions for the Neutral Technology in Enkanini
Each scenario represents an integrated dynamic analysis of the (i) standard of sanitation in
informal settlements, (ii) population, (iii) user temperament (related to sanitation), (iv) number of
toilets and (v) the sanitation experience/senses fulfilled (dignity, safety, privacy etc.) for a
different technology.
5.1 Comparative results for standard of sanitation
Figure 7 represent comparative results of the four different technology options and the neutral
technology for the standard of sanitation, senses fulfilled the number of toilets and the user
temperament. Each of these are key indicators within the system that allow for a more effective
conceptualisation of the current standard of sanitation in Enkanini as well as an analysis of the
possible influences that new technologies could have on the situation.
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Figure 7: Comparison of Technologies: Standard of sanitation
From Figure 7, it can be seen that with the introduction of compost toilets the standard of
sanitation quickly improves within the settlement. On the other end of the scale it is seen that the
traditional waterborne technology will take the greatest amount of time to influence the standard.
All of the different technologies increase the standard of sanitation at different rates before
flattening out at 0.4; this is due to the fact that the model does not allow them to surpass the
minimum expectation for sanitation of 0.4. A minimum expectation was added to account for
seeing the green grass over the fence. For the baseline, it’s at 0.4, meaning that if sanitation dips
far below that, users will do something about it.
This is one of the limitations of the model as it proved very difficult to accurately and effectively
model expectation. This graph does however illustrate how different technologies will address
the sanitation problem at different rates; it also indicates the possible need of another policy
intervention should the sanitation level become stagnant at a low level.
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5.2 Sanitation Experience/senses fulfilled
Once again it is observed that the different technologies influence the sanitation experience at
different rates with the waterborne ending well above the other options and the compost toilet
well below. This fulfills the original mental model, staying true to what was expected as shown
in Figure 8. It also is something for policy makers to consider when addressing sanitation; these
differences in sanitation experience are as important as addressing the physical sanitation needs
of a people. Awareness of this may reduce instances of protest or occurrences of ‘poo wars.’
Figure 8: Comparison of Technologies: Sanitation Experience/senses fulfilled
5.3 Number of toilets
Figure 9 represents the stock of toilets for each technology. The stock of toilets increased by a
flow of new toilets and decreased by flows of decommissioned toilets and toilets destroyed
through vandalism. Each technology has a different cost per unit as well as decommissioning
rate hence the difference on the graph. Compost toilets are relatively cheap and have a slow
decommissioning rate. Whereas waterborne technology carries a high unit cost and an average
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decommissioning rate resulting in fewer toilets over time. The rate of toilet growth slows as the
sanitation level stabilizes.
Figure 9: Comparison of Technologies: Number of toilets
5.4 User temperament
The gap between expected and actual sanitation determines the user temperament. Given the rate
at which compost toilets can be produced (low cost price) this technology has a quick influence
on the standard of sanitation in the informal settlement thus reducing the gap and improving the
temperament. Waterborne toilets take long to build therefore influence the standard of sanitation
and thus the user temperament at a slower rate. Figure 10 shows that user temperament results in
leveling out of the sanitation standards.
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Figure 10: Comparison of Technologies: User Temperament
5.5 Causal interactions for the Neutral Technology in Enkanini
Taking into account the before mentioned parameters of Enkanini and a neutral technology the
following results were obtained for the following indicators; number of toilets, population,
senses fulfilled, standard of sanitation, user temperament, accountability and cleanliness of
facilities.
Figure 11 demonstrates the workings of the model for the Enkanini case study. “The turquoise
line shows a steady exponential population growth over time with a monthly budget of R19166,
about 3.8 neutral tech toilets can be built a month (blue line). This tapers off as the sanitation
level (black line) stagnates, but continues to grow to address population growth. The initial
introduction of toilets improves the user temperament (brown line) which improves the standard
of sanitation. Poor user temperament ensures high service provider accountability (red line),
which keeps cleanliness (green line) high; the fluctuations in cleanliness are caused by the
fluctuations in user temperament which determine how users care for the facilities. Finally,
27
sanitation experience (grey) is seen growing then leveling out. This Figure demonstrates the
average of all the other technologies combined.
Figure 11: Key Variable Comparison: Enkanini Neutral Technology.
All of the technology scenarios tested showed an obvious positive improvement with regards to
sanitation experience, the standard of sanitation and user temperament, albeit at different rates.
They show what we would expect: that new facilities will have an impact on health and
sanitation of world slums. It further demonstrates that the type of technology is vitally important
for achieving sanitation goals, particularly in addressing the sanitation experience and balancing
the costs and benefits of each technology.
6 Conclusion
This paper utilised systems dynamics to conceptualise the current standard of sanitation in
Enkanini informal settlements as well as analyse possible influences that new technologies could
have on the situation. The analysis is based on an understanding of internal and external
interactions within the informal settlement, and the induced changes in its properties over time.
28
The application of the model to Enkanini was a useful demonstration of the model’s strengths
and limitations. The different scenarios produced unique results yet they all showed a common
improvement with regards to the standard of sanitation in informal settlements, confirming to the
world understanding that providing functioning facilities will improve sanitation. This however
does not take into account the importance of context specific solutions and the sanitation
experience which we believe to be a vital element of sanitation solution.
The model successfully demonstrated differences between the various technologies, suggesting a
long-term benefit from waterborne sanitation, while showing the rapid improvement in sanitation
from cheaper options of a compost toilet and ventilated improved pit latrine. The pour flush toilet
and vent pit latrine occupied the beneficial middle ground of minimal investment for decent
output in sanitation improvement as well as improvement of the sanitation experience.
Application to the case study also demonstrated the difficulty of modelling expectations as well
as drawing out faults in the magnitude of certain variables’ feedbacks into the system.
Prevalence for disease had a greater impact on death rate than feasible, and will warrant some
expert consultation. Within the bounds of the limitations, useful information was gleaned and
further learning was afforded to the authors.
Using this model to analyse the major dynamics in informal settlement sanitation demonstrated
that seeing the sanitation problem as merely a technical fix will not suffice. True change will
require a transformation in how users and service providers approach the problem of sanitation,
taking into account community demand, community temperament and actions, functionality,
dignity, safety and attached value. This is truly one of the pressing challenges of the 21st
Century.
Finally, this is still work in progress and the model is will further be refined through engaging
with various stakeholders.
29
References
BARLAS, Y. (1996) Formal aspects of model validity and validation in system dynamics. System
Dynamics Review, 12, 183-210.
CITY OF CAPE TOWN. ( 2008) Water and sanitation service standard. Available online:
http://www.capetown.gov.za/en/Water/Documents/Water%20and%20Sanitation%20Service%20
Standards.pdf [26 January 2014].
FORD, A. (2010) Modeling the environment, Washington DC, USA, Island Press.
ISHACKLIVING (2012) Water and sanitation. Available online: http://ishackliving.co.za/blog/?p=24
[accessed 1 October, 2013].
KATUKIZA, A. Y., RONTELTAP, M., NIWAGABA, C. B., FOPPEN, J. W. A., KANSIIME, F. &
LENS, P. N. L. (2012) Sustainable sanitation technology options for urban slums. Biotechnology
Advances, 30, 964-978.
KATUKIZA, A. Y., RONTELTAP, M., OLEJA, A., NIWAGABA, C. B., KANSIIME, F. & LENS, P. N.
L. (2010) Selection of sustainable sanitation technologies for urban slums - A case of Bwaise III
in Kampala, Uganda. Science of The Total Environment, 409, 52-62.
MAANI, K. E. & CAVANA, R. Y. (2007) Systems thinking & modeling: understanding change and
complexity, New Zealand, Pearson.
MELS, A., CASTELLANO, D., BRAADBAART, O., VEENSTRA, S., DIJKSTRA, I., MEULMAN, B.,
SINGELS, A. & WILSENACH, J. A. (2009) Sanitation services for the informal settlements of
Cape Town, South Africa. Desalination, 248, 330-337.
PATERSON, C., MARA, D. & CURTIS, T. (2007) Pro-poor sanitation technologies. Geoforum, 38, 901-
907.
RANDERS, J. (1980) Guidelines for model conceptualization. IN RANDERS, J. (Ed.) Elements of the
system dynamics method. Cambridge, MIT Press.
RICHARDSON, G. P. & PUGH, A. L. (1981) Introduction to system dynamics modeling with DYNAMO,
Cambridge, Productivity Press.
ROBERTS, N. H., ANDERSON, D. F., DEAL, R. M., GRANT, M. S. & SHAFFER, W. A. (1983)
Introduction to computer simulation: the system dynamics modeling approach, Reading, MA,
Addison-Wesley.
ROBINSON, B., SWILLING, M., HODSON, M. & MARVIN, S. (2013) City-Level decoupling: urban
resource flows and the governance of infrastructure transitions. Report for Cities Working Group
of the International Resource Panel, United Nations Environment Program. Available online:
http://www.unep.org/resourcepanel/portals/24102/Decoupling/City-
Level_Decoupling_Summary.pdf [accessed 27 January 2013].
SHACK DWELLERS INTERNATIONAL. (2012) Enkanini (Kayamandi) household enumeration report.
Available online: http://sasdialliance.org.za/wp-
content/uploads/docs/reports/Enumerations/Enkanini%20Final%20Report.pdf [accessed 26
January 2012].
SOCIO-ECONOMIC RIGHTS INSTITUTE OF SOUTH AFRICA (SERI). (2011) Basic Sanitation in
South Africa: a guide to legislation, policy and practice. Socio-Economic Rights Institute of
South Africa. Available online: http://www.pan.org.za/node/8224 [accessed 27 January 2014].
STERMAN, J. D. (2000) Business dynamics: systems thinking and modelling for a complex world, New
York, McGraw-Hill/Irwin.
TAVENER-SMITH, L. (2013) Personal Interview. 20 September 2013, Stellenbosch, Western Cape. .
UNEP. (2012) Sustainable, resource efficient cities - making it happen! Available online:
www.unep.org/urban_environment/PDFs/SustainableResourceEfficientCities.pdf [accessed 6
March 2013].
UNITED NATIONS DEPARTMENT OF ECONOMIC AND SOCIAL AFFAIRS. (2010) World
Urbanization Prospects: The 2009 Revision, Highlights. , Population Division, New York.
WOLSTENHOLME, E. (1990) System enquiry: A system dynamics approach, Chichester, Wiley.
30
WORLD HEALTH ORGANISATION. (2012) Water sanitation health. Available online:
http://www.who.int/water_sanitation_health/monitoring/jmp2012/key_terms/en/ [accessed 1
October 2013]